PLATE
meter current:
I'm not sure why
Johnson did this,
maybe they had no
choice, but the
PLATE meter position
does not read plate
current. In the
plate
position, the meter
actually reads all
current to the
screen grid clamp
tube system, the 6146
screen grid, and
any current through SW4A
to ground in the
TUNE mode. Since R15
is 30Kohms and HV
can be 550 volts or
so, there is about
20 mA of "false" PA
current. That
"false" current is
reduced under full
power RF operation
by about 10 mA or
so, where the clamp
tube is off. The
normal operating
plate current at
full power mostly
includes only plate
and screen current.
Under all other
conditions though
the plate meter is
very misleading.